<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    #dad {
      width: 300px;
      height: 300px;
      background-color: #489EE2;
    }
    .son {
      width: 300px;
      height: 150px;
      background-color: #b7d4a8;
    }
    
  </style>
</head>
<body>
<div id="dad">
  <div class="son">1</div>
  <div class="son">2</div>
</div>
</body>
</html>
